On Tue, Apr 02, 2002 at 12:59:40AM -0800, Pavan Kumar Achanta wrote:
> I was tring to implement the standard pedagogictime system
> call from 'nutt'.. It got compiled but got an error :
>
> Error while loading shared libraries : libc.80.6 Cannot
> stat shared object: Error 14 /sbin/mingetty
>
> when I restart with the new kernel image
> And this is what I did .....
>
>
> ********* step1 *******************
> /usr/src/linux/arch/i386/kernel/entry.S
>
> .data
> ENTRY(sys_call_table)
> .long SYMBOL_NAME(sys_ni_syscall) /* 0 - old "setup()"
> system call*/
> .long SYMBOL_NAME(sys_exit)
> .long SYMBOL_NAME(sys_fork)
> .long SYMBOL_NAME(sys_read)
> .long SYMBOL_NAME(sys_write)
> .long SYMBOL_NAME(sys_open) /* 5 */
>
> ..................
>
> .long SYMBOL_NAME(sys_ni_syscall) /* streams1 */
> .long SYMBOL_NAME(sys_ni_syscall) /* streams2 */
> .long SYMBOL_NAME(sys_vfork) /* 190 */
>
> .long SYMBOL_NAME(sys_pedagogictime) /* 191 */
>
> .rept NR_syscalls-191 //change number -190 to -191
> .long SYMBOL_NAME(sys_ni_syscall)
> .endr
>
> it was NR_syscalls-221 and changed it to NR_syscalls-191
Funny, the number should have increased! I mean, when you added
a syscall, you must have had shotened the padding at the end.
Ie. if there was NR_syscalls-221, then it should end up as
NR_syscalls-222. And your syscall should have had number 222.
> //********* step2 *******************
> And one more line to file /usr/src/linux/include/asm/unistd.h
>
> #define __NR_sigaltstack 186
> #define __NR_sendfile 187
> #define __NR_getpmsg 188 /* some people actually want
> streams */
> #define __NR_putpmsg 189 /* some people actually want
> streams */
> #define __NR_vfork 190
> #define __NR_pedagogictime 191 /*Bill add this line for lab4 */
>
>
> Here I didnt know what to do about the already existing
> #define __NR_mmap 191 so I just kept it as it is..
Funny... I see (kernel 2.4.17):
#define __NR_ugetrlimit 191 /* SuS compliant getrlimit */
#define __NR_mmap2 192
And IIRC syscall's can't be renumbered, because that would require
recompilation of libc.
> Can somebody tell me what the line
Choose different number; this one is already in use!
> .rept NR_syscalls-191 //change number -190 to -191
> .long SYMBOL_NAME(sys_ni_syscall)
> .endr
In 2.4.17, I see:
.rept NR_syscalls-(.-sys_call_table)/4
.long SYMBOL_NAME(sys_ni_syscall)
.endr
Which is The Right Thing. Which kernel version are you using?
> means and how the whole thing works!!! and what is the right
> way to add a system call ....
You just have to pick an unused number. The one you used seems not to be
a good one.
--------------------------------------------------------------------------------
- Jan Hudec `Bulb' <bulb@ucw.cz>
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
